Authors: DIMITRA BOBORI, OLGA PETRIKI, EMMANOUEL TSAKOUMIS
Abstract: The cyprinid Pachychilon macedonicum (Steindachner, 1892) is a species that is endemic to the southern Balkan Peninsula with limited distribution in Greece. Here we confirm the species' expansion and establishment in a complex of 4 lakes located outside of its currently known distribution range and provide, for the first time, some of its biological features. The species' presence was certified in 3 (Vegoritida, Petron, Chimaditida; northern central Greece) of the 4 lakes studied (Lake Zazari was also sampled), which now constitute a new western limit for its distribution in Greece. Pachychilon macedonicum specimens in Lake Vegoritida were longer (mean length: 5.8 ± 0.04 cm) than those in Lake Petron (mean length: 5.5 ± 0.05 cm), with the longer and heavier specimens recorded from depths of between 9 and 12 m in Lake Vegoritida (ANOVA, P < 0.001). The highest rate of individuals per 100 m2 of nets (NPUE) and weight of individuals per 100 m2 of nets (BPUE) were observed in the upper depth strata (0-3 and 3-6 m). The densities, in terms of NPUE, as well as the extracted length-frequency distributions, show evidence for the species' establishment in Lake Vegoritida and for a newly existing population in Lake Petron. The estimated length-weight relationships revealed positive allometric growth of the species in both lakes, Vegoritida (b = 3.3235) and Petron (b = 3.4594). In general, Pachychilon macedonicum exhibited an adaptive selection to littoral environments and an occupation of the epilimnion, avoiding the deeper water strata.
Keywords: Range expansion, southern Balkan Peninsula, Pachychilon macedonicum, length?weight relationship, NPUE, vertical distribution
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